Alkenes undergo a variety of oxidation reactions. With cold and neutral or alkaline `KMnO_(4)`, alkenes are oxidised to give vicinal diols. Oxidation with hot `KMnO_(4)` undergoes cleavage of C=C bond leading to the formation of carboxylic acids, ketones and carbon dioxide depending on the nature ofalkene. Reductive ozonolysis of alkenes give aldehydes or ketones.
An alkene 'X' on treatment with hot alkaline `KMnO_(4)` gives acetic acid. Alkene X' is

Options

A. Hex-3-enc
B. But-2-ene
C. But-1-ene
D. Pent-1-ene

Explanation

To determine the alkene 'X' that, when treated with hot alkaline KMnO₄, gives acetic acid, we will analyze the oxidation reactions of various alkenes.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- When alkenes react with hot alkaline KMnO₄, they undergo oxidative cleavage of the C=C double bond. This results in the formation of carboxylic acids, ketones, and possibly carbon dioxide, depending on the structure of the alkene.

2. **Identifying Acetic Acid**:
- Acetic acid (CH₃COOH) has two carbon atoms. Therefore, for the alkene 'X' to yield acetic acid upon cleavage, it must break down into two molecules of acetic acid.

3. **Analyzing Possible Alkenes**:
- Let's consider the options provided:
- **Hex-3-ene**:
- Structure: CH₃-CH₂-CH=CH-CH₂-CH₃
- Cleavage will yield propanoic acid (CH₃CH₂COOH) and another product, not acetic acid.
- **But-2-ene**:
- Structure: CH₃-CH=CH-CH₃
- Cleavage will yield two molecules of acetic acid (CH₃COOH).
- **But-1-ene**:
- Structure: CH₂=CH-CH₂-CH₃
- Cleavage will yield butanoic acid (CH₃CH₂CH₂COOH) and formic acid (HCOOH), not acetic acid.
- **Pent-1-ene**:
- Structure: CH₂=CH-CH₂-CH₂-CH₃
- Cleavage will yield butanoic acid and formic acid, not acetic acid.

4. **Conclusion**:
- The only alkene that produces acetic acid upon oxidation with hot alkaline KMnO₄ is **But-2-ene**.

### Final Answer:
The alkene 'X' is **But-2-ene**.